Passenger vehicles and trucks incorporate a powertrain having a multi-speed transmission. Generally, these transmissions have been planetary or countershaft-type transmissions providing a multitude of ratios somewhere between two and seven ratios.
To reduce the number of ratio interchange events, it has been considered that variable ratio transmissions would be advantageous. Variable ratio transmissions have continuous ratio changes, such that the event of a ratio interchange is not evident. These variable transmissions or continuously variable transmissions (CVTs) have taken the form of hydraulically variable units, electrically variable units, and friction belt units. These transmissions lend themselves well to improve fuel economy and vehicle performance.